Former national security adviser Michael Flynn has asked for a 90-day delay in his sentencing for lying to the FBI. File Photo by Mike Theiler/UPI | License Photo

March 13 (UPI) -- Former national security adviser Michael Flynn has finished working with Justice Department investigators looking into Russian electoral interference, and now faces sentencing this month for lying to the FBI in the case.

The office of special counsel Robert Mueller said in a status update late Tuesday that investigators have finished their work with Flynn as it pertains to Russia, a primary figure in the inquiry.

Flynn and Mueller's office were given until Wednesday to update the court on his cooperation.

Mueller's office is investigating whether Moscow interceded in the 2016 U.S. election and whether Trump campaign officials were involved.

Flynn faces prison for lying to the FBI about contacts with Russian ambassador Sergey Kislyak a month after President Donald Trump was elected. He said the discussions focused on potentially lifting Obama-era sanctions on Russia. Flynn had called Kislyak five times, but did not disclose the talks to federal agents or during his confirmation process to be Trump's national security adviser. He was ultimately dismissed from the post for it.

With his cooperation on the Russia probe complete, Flynn is now asking for a 90-day delay in sentencing in case he needs to cooperate in another case involving former business partner Bijan Rafiekian. Sentencing was first set for December but postponed to March so he could continue working with investigators. Flynn filed for another delay for the same reason.

"However, while the defendant remains in a position to cooperate with law enforcement authorities, and could testify in the [Rafiekian] case should it proceed to trial, in the government's view his cooperation is otherwise complete," Mueller wrote in a letter.

Judge Emmet Sullivan has said he would consider Flynn's 33 years of military service at sentencing, but maintained his crimes were "very serious."

"Arguably, you should your country out. The court's going to consider all that," Sullivan told Flynn in December. "But I'm not hiding my disgust, my disdain for this criminal offense."